Darwin's Finches: Galapagos Islands

November 24, 2008 marks the 149th anniversary of the release of Charles Darwin’s infamous book “On the Origin of Species by Means of Natural Selection”. In honor of this anniversary, I thought it appropriate to write about Darwin’s finches and the Galapagos Islands.

When Charles Darwin comes up in conversation (it does happen, I promise), mention of the Galapagos Islands is sure to follow. The Galapagos have been described as a world within themselves. The islands are home to unique species like giant tortoises, equatorial penguins, and swimming iguanas. Darwin’s finches are also famous residents of the islands.


Darwin visited the Galapagos for five weeks in 1835 as he worked as a ship’s naturalist aboard the HMS Beagle. While exploring the islands, he collected a variety of plants and animals to study in greater detail later on. Upon his return home to England, he passed his feathered collection along to the renowned ornithologist John Gould for further examination. Gould categorized the finches he received into 13 species. All of the finches were remarkably similar in morphology except for their beaks.

Darwin was dumbfounded by Gould’s findings. Could it be that the 13 species had evolved from a single ancestral finch? The answer is yes, and the finches helped serve as a springboard to Darwin’s scientific breakthrough – nature selects for characteristics that make organisms better adapted to their environment, changing populations over time.


The beak is an avian necessity for handling and manipulating food. For anyone that’s ever put out birdfeeders for a little backyard birding, you know that different seeds attract different birds. Goldfinches love thistle, hummingbirds love nectar, and jays love peanuts. Sunflower seeds, an all-purpose food, are attractive to a variety of species.

When you live on islands that are geologically young like the Galapagos, there isn’t a wide variety of food available. Darwin described the islands as “a scattering of rocks with the scrubbiest of vegetation”. A finch that lives on the islands and eats the same food as all of the other finches faces fierce competition. Competition is a lose-lose situation. Character displacement, evolutionary changes in species to minimize competition, may best be seen in the beaks of Darwin’s finches.

Among the 13 species of finches on the Galapagos, you can see cactus finches, a vegetarian finch, ground finches, tree finches, and even a woodpecker finch. Just by reading the list of names, you get an idea of their food preferences, all of which are slightly different. Less competition often leads to greater reproductive success, the goal of survival.


If you make it to the Galapagos and come across some of Darwin’s finches, pause for a moment. You just might see the beak of the finch in action.

Monarch Butterfly Biosphere Reserve: Mexico

Monarch butterflies (Danaus plexippus) are notable for their long-distance migrations. The fact that an insect measuring a fifth of the weight of penny can fly a journey totaling up to 3,000 miles is amazing. What’s even more impressive is that the individuals that make the journey south have never been to their winter destination before.

Every year millions and millions of monarchs in North America, east of the Continental Divide, migrate to central Mexico to spend the winter months. These butterflies aren’t the same individuals that journeyed north earlier in the year. They’re the great, great grandchildren (grand-butterfly?) generation. The butterflies appear to fly on pure instinct, and the oyamel fir (Abies religiosa) forests in the states of Michoacan and Mexico are apparently an irresistible pull for the monarchs. Only monarchs born in the late summer or fall make the southward migration.


Larval monarchs feed on milkweed plants (Asclepias spp.) after they hatch from eggs. Milkweeds contain a noxious sap that makes monarchs, in turn, unpalatable to potential predators. Adult monarchs feed on nectar, but their high contrast coloration is a warning sign to potential predators of toxicity stemming from their larval days.

The range of oyamel firs in Mexico is extremely limited. The species is only found on 12 isolated mountaintops in Mexico’s Transverse Neovolcanic Belt. Oyamel forests are wet and cool and this environment helps slow the metabolism of monarchs so they can conserve food reserves throughout the winter to make the journey northward in the spring.

Milkweed population declines in North America and deforestation in the Mexican wintering grounds are leading to a decrease in monarch numbers. The 2008 designation of the Monarch Butterfly Biosphere Reserve in Mexico by the United Nations Educational, Scientific, and Cultural Organization (UNESCO) is an attempt to protect valuable monarch winter habitat from further destruction.

Dias de los Muertos: Mexico

Today and yesterday, November 1st and 2nd, mark the Days of the Dead (Dias los Muertos) in Mexico. November 1st is in honor of deceased children and infants (Dia de los Inocentes – Day of the Innocents) and November 2nd is in honor of adults (Dia de los Muertos).


Whenever I bring up Day of the Dead in conversation, it’s usually met with a response that insinuates morbidity. In fact, Day of the Dead is quite the opposite. Families and friends gather on these two days to celebrate the lives and memories of loved ones that have been lost over the years. It is a celebratory holiday and one of my most memorable travel experiences was a trip to Michoacan, Mexico to partake in the festivities.

Mexican legend has it that people die three deaths. The first death occurs when our body ceases to function. The second death happens when our body is buried, returned to the earth, and placed out of sight. The third, and final death, ensues when there is no one left to remember us. Dias de los Muertos is a way to keep the third death from coming to pass.


Over the two Days of the Dead, it is believed that the souls of the deceased find it easier to visit lost family members and friends. Because of this, people visit cemeteries in anticipation of this annual return. Altars are erected at the grave site and ofrendas (offerings) of the deceased’s favorite foods and libations are placed on the altars - enticement and sustenance for the soul’s long journey. Dias de los Muertos is a celebration of life as the thought of death is embraced and accepted.


If you ever have the opportunity to visit Mexico during this time of year, it’s an experience that provides insight into a national tradition that blends a variety of cultures spanning thousands of years. In the process, Dias de los Muertos just might change the way you view death.